Electric stock fencer



T. E. JOHNSTON ELECTRIC STOCK FENCER Filed July 13, 1964 May 21, 1968\HHHHH IN VEN TOR. B Eda W570 United States Patent 3,384,788 ELECTRICSTOCK FENCER Thomas E. Johnston, 605 N. Main, Shamrock, Tex. 79079 FiledJuly 13, 1964, Ser. No. 382,297 3 Claims. (Cl. 307-132) ABSTRACT OF THEDISCLOSURE Electric stock fence charger having an RC circuit including aresistance and a capacitance connected to a current supply, a triggercircuit to discharge the capacitor through a vibrator reed relay, andmeans to energize a primary winding when the contacts of the vibratorare open and a shorting circuit for the winding.

This invention relates to an improved electric stock fence charger, andmore particularly to a transistor relaxation oscillator fence chargerhaving improved simple circuitry for providing reliable and efiicientoperating characteristics without providing any criticality in thearrangement or connection of the parts of the circuit charger.

The fence charger of the invention uses many standard and readilyavailable parts. The inductance relays may have a resistance of from 50to 400 ohms, and a vibrator can be used that is readily found in manyautomobile radio sets. The power or output transistor may be one that isreadily found in audio output circuits of many automobile radios andtransistor power amplifiers. A modification of the invention providesfor a coil in therelaxation portion of the circuit that may be from 500to 1500 ohms resistance, and may draw about 7 to 12 milliamperes. Theresistance of the relaxation circuit need be merely enough to allow theproper amount of current to charge the condenser of the RC circuit.

One of the important advantages in using transistors in a fence charger,and especially in the output stages thereof, is that the currentdrainage through the points of the coil vibrators and across the circuitcontacts is very low in current, and for this reason these contactpoints may last a lifetime in the fence charging circuit. Due to theintermittent operation of the coils in the discharge path of the RCcircuit, the average power for any given period is very inconsequential,and therefore a battery power or a low source of A.C. current mayreadily be used.

Among these advantages, it is also found that the invention provides forproducing a pulsating stepup voltage derived from a relay arrangement sothat there is derived a modern fence charger that can readily andefficiently be operated from dry cells, or a wet battery current source,or even a small A.C. current power pack that may derive its power fromline current of 117 volts A.C.

Another object of the invention is to provide an improved electric stockfencer comprised of a new transistor circuit for producing a hotter,more efiicient and longer life equipment that is trouble-free and hasless current consumption for providing longer life to the contact pointsthat may be used in the fence charger.

In the improved fence charger of the present invention, it is seen thatthe fence charger is often used at the beginning of a season or periodin which stock are sought to be maintained within the fencing, duringwhich time the animals or stock find that the fence is hot. The fenceris then operated with a pulsating charge or spark of possibly to 15shocks, and such pulsations or intervals occur approximately 48 timesper minute. This pulsating current by a vibrator may be a low frequencypulsation unit delivering a substantial shock, rather than a sting orburn, but is often produced by many of the higher powered electricfencing equipment. The apparatus of the present invention is found notto harm surrounding environmental vegetation which is kept green butdoes not short out the fence to ground. Since the present inventionoperates from a substantially low frequency, it does not cause grassfires when the grass is somewhat dry, as is the case with fence chargersof the prior art.

In the practice of the present invention, the circuit may be changedfrom a rapid to a slow rate so that once the animals are made aware thatthe current is on the fence, the current can be switched to the singlespark position, thereby achieving a small saving in battery drain.

A further object of the invention is to provide a 12 volt battery or arectifier operated from a 117 volt A.C. current with a minimum DC. powerdrain.

These and other objects of the present invention will become apparentfrom a detailed description of the invention and from the appendeddrawings and claims.

In the drawings, the figure shows a circuit schematically showing theessential and important features of the improved electric stock fencercircuit, which is a preferred embodiment of the present invention.

Referring now to the drawings, the figure shows a source 10 which is aconventional 12 volt battery which may be of the dry or wet type. Thereis also shown as an alternative source 10a which may be connected asshown in dotted lines 12, 12 that provides for connecting the source 10ato the electric fencer in lieu of using the battery source 10. Thesource 10a comprises a full wave rectifier 14 that converts alternatingcurrent from a power line 16 to a 12 volt D.C. characteristic.

The source 10 is shown connected to an RC circuit comprising resistanceR1 and condenser C100. The resistance R1 is provided with a tapconnection for varying the value and time constant of the RC circuit.The condenser C is charged substantially to its peak voltage during acharging time controlled by the value of the resistance R1, and theelectric field about the primary of T1 is established generallyconcurrently in time to the charging of C100 through the rectifier, andin a given case the charging time may be 48 times per minute. When thcondenser is substantially charged completely, a trigger transistor X1,being of the unijunction type, is triggered by the value of the chargeon condenser C100 so that it discharges the condenser through eitherrelay L1 or L2 depending upon the position of thesingle-pole-doublethrow switch SW1. The switch SW1 is shown in the UPposition so that the discharge of capacitor C100 is connected throughreed relay L2 to the trigger transistor X1, and the armature or reed ofthe relay L2 is seen to vibrate several times due to the energization ofthe coil of the reed relay L2. The vibration of the armature of relay L2makes and breaks the sets of contacts 1-2 and 3-4 so that the trigger orunijunction transistor X1 is grounded through contacts 3-4, and thecontacts 1-2 when similarly closed provide for a shunt path to ground ofthe collapse current that may be generated in a primary winding or highvoltage spark coil at T1 that is connected between ground and the highside of the power source 10 through a rectifier 20. While the rectifier20 provides for a conductive path from the source through the primarywinding of the high voltage spark coil T1, the collapse current is seento be discharged or carried off through a transistor X2 by itsbase-collector circuit through the closed contacts, when such is thecase, of contacts 1-2 to ground.

Similarly, with the switch SW1 in the DOWN position, the triggerunijunction transistor X1 then delivers through the reed relay L1 acurrent for causing the current to pass through contact points 5-6 forsimilarly discharging only the collapse current that is provided in theprimary winding of the high voltage spark coil T1. This provides adifferent and varied rate of spark in the high voltage spark coil. Thehigh voltage spark coil T1 includes a secondary winding 24 which isconnected to the fence element 26 in a well known manner. The other endof the winding 24 is connected to ground, as is also Well known.

The operation is as follows: When one of the trigger points 2 or 6 isconnected to ground or negative polarity, X2 is forward biased throughthe 10 and 12 ohm resistors and X2 base junction. X2 then switchesbetween its emitter and collector circuit letting a large pulse ofcurrent pass from the plus junction 12 through emitter and collector andout into the primary coil of T1. At this time, the trigger points 2 or 6break the circuit to the base junction of X2 which takes away theforward bias on the base of X2 causing the collector and emitter circuitin X2 to separate or switch olf. This interruption causes a quick riseof the voltage in primary coil 18 and with a reverse of polarity, diode20 with its polarity indicated is placed across collector and emitter ofX2 to protect X2 from this erratic voltage. The excessive voltage passesthrough 20 back to plus side 12. Transformer T1 steps up the voltage andconnects with the fence wire.

It is apparent that the examples and modifications shown and describedabove have been provided solely by way of illustration and not by way oflimitation, and these exemplary descriptions of the invention arevariations and modifications within the scope of the present inventionas defined and set forth in the accompanying claims.

What is claimed is:

1. Electrical fencing equipment comprising an RC circuit including aresistance and a capacitance for connection to a source of currentsupply, means for charging the capacitance,

an inductive discharge path including a vibrator reed relay,

a unijunction transistor trigger circuit coupled to the capacitance ofsaid RC circuit to discharge the RC circuit through a vibrator reedrelay of said inductive discharge path,

said reed relay having contacts that are opened and closed byoscillations of the armature thereof,

transistor means responsive to the opening of said contacts for applyinga current to a primary winding, and

a rectifier circuit connected across said transistor means andresponsive to the closing of said contacts for switching the primarywinding to shorted relation.

2. Electrical fencing equipment comprising an RC circuit including aresistance and a capacitance for connection to a source of currentsupply, means for charging the capacitance,

a vibrator reed relay energizable upon discharge of the capacitance ofthe RC circuit,

a trigger means coupled to the RC circuit to couple the discharge of thecapacitance thereof to the vibrator reed relay,

said vibrator reed relay having contacts that are opened and closed uponoscillations of the armature thereof,

transistor means responsive to the opening of said contacts for applyinga current to a high voltage spark coil, and

a rectifier circuit connected across said transistor means andresponsive to the closing of said contacts for shorting the collapsecurrent of the high voltage spark coil to ground.

3. Electrical fencing equipment of claim 2 wherein the trigger circuitis a reed relay, and in which said source is a battery.

References Cited UNITED STATES PATENTS 2,594,595 4/1952 Stearns 32l49 X2,685,056 7/1954 Hester 321-49 3,115,610 12/1963 Beguin 331-111 X3,182,227 5/1965 Brittain et a1 317--148.5 3,202,884 8/1965 Bullock317-1485 3,218,793 11/1965 Walton 331-116 ORIS L. RADER, PrimaryExaminer.

T. B. JOIKE, Assistant Examiner.

